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An Integrated Load Balancing Scheme for Future Wireless Networks

An Integrated Load Balancing Scheme for Future Wireless Networks. Instructor: 陳仁暉 Student: 連挺鈞 Wireless Pervasive Computing, 2009 ISWPC GLOBECOM Workshops, 2008 IEEE. Outline. Introduction Related Work Contribution Proposed Scheme Scheme Propagation Scheme Network Flow Simulation

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An Integrated Load Balancing Scheme for Future Wireless Networks

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  1. An Integrated Load Balancing Scheme for Future Wireless Networks Instructor: 陳仁暉 Student: 連挺鈞 Wireless Pervasive Computing, 2009 ISWPC GLOBECOM Workshops, 2008 IEEE

  2. Outline • Introduction • Related Work • Contribution • Proposed Scheme • Scheme Propagation • Scheme Network Flow • Simulation • Result • Conclusion

  3. Introduction • Focus on delay sensitive traffic • Excessive handover latency and packet loss • Overloading AP suffers from high delay • Can’t guarantee real-time services under heavy loads • Dynamic network • Suffers high packet delay and packet loss • Goal • Throughput and QoS fairness

  4. Related Work (1/2) • Metrics • Num. of active connections, gross load, packet loss and throughput • Circuit-Switched • Bianchi et al [7] • WLAN can be improved by using additional packet level • Bazzi et al [8] • CAC denying incoming calls when low resources • Disadvantage • Not adaptive to dynamic network condition

  5. Related Work (2/2) • Centralized (Balachandran et al. [9]) • Centralized admission control servers • Load information of all APs • Disadvantage • Increase signaling overhead • Creates bottleneck • Prone to single point of failure • Decentralized (Velayos et al. [10]) • Using throughput per AP as load metric • Disadvantage • Can only reassociate with underloaded AP

  6. Contribution • Guarantee service QoS during handover • Enabling seamless handover • Operate network in unsaturated mode with soft admission control • Select best target network • Network-assisted discovery compatibility with IEEE 802.21 media independent handover infrastructure • Single transceiver stations, horizontal and vertical handovers

  7. Propose Scheme (1/2) • Bootstrap approximation • Est. short-term stationary dynamic QoS parameters in AP • Sequential Bayesian estimation • Estimate probability density function • Station select best AP according to delay est. • Obviate detection and scanning • Latency reduction • Protects existing connection • Soft admission control • Important for multimedia traffic

  8. Propose Scheme (2/2) • Shaded block • Network entry • Unshaded block • Terminal entry • Trigger • Initial access • Choose best network according to packet delay requirement • Handover • Packet loss rate exceeds 2% for VoIP • Soft admission control monitors source and target AP • Stability period: 10 beacon intervals

  9. Scheme Propagation • Measure report • Access point controller (APC) • Using location based broadcast • Monitor source AP • Advantage • Monitoring AP w/o APs exchanging information • Eliminate scanning • Consists of two-way handshake • Soft admission control: 1ms • Avg. channel switch time: 12 ms • Authentication delay: < 1ms • Avg. reassociation delay: 15.37ms

  10. Scheme Network Flow

  11. Simulation (Topology) • Basic settings • Codec delay: 40ms • Packetization delay: 20ms • Backbone network delay: 30ms • Wireless network delay: < 60ms • 802.11b(11Mbps), 802.11g(54Mbps) • At least 1 legacy link to 11g • OPNET Modeler 14.0 with Wireless Module • No hidden terminal • MSDU life time: voice(50ms), video(100ms), data(1s) • No mobility

  12. Simulation (Process) • Initial (Unbalanced load) • 2 FTPs, 2 videos • 7 G.711 stations in BS1 • 7 G.711 stations in BS2 • 900s • Additional 1 FTP, 1 video • 5 G.711 from BS1 stopped • 5 G.711 from BS2 start

  13. Result (Settings) • Examine QoS performance • Delay and packet loss of AP • Quantify effect of load balancing • xi: total throughput or delay of access point I • n: number of access points after redistribution • Balanced index • 0: APs extremely unbalanced, n  inf • 1: APs same throughput or delay, 1/n

  14. Result (Packet loss rate) • iLB: integrated load balancing • 802.11b/g: DCF • 802.11e: EDCA • Focus on avg. downlink delay and packet loss rate

  15. Result (Throughput and delay) • Balance index • Throughput • DCF and EDCA: 0.86 • iLB: 0.96 • Delay • DCF and EDCA: 0.56, 0.58 • iLB: 0.81

  16. Conclusion (1/2) • This paper provides a thorough investigation • System model, propagation, network flow • Simulation on known model (OPNET) • Simulation model • Mathematical approach • Focus on one topic • Delay and packet loss over vertical handover • Specific on the system settings

  17. Conclusion (2/2) • Disadvantage • Still have lots of overhead from APC • No comparison with other load balancing scheme • No robust data flow • Similarity • APC as to ABS • APs as to femto BS • Difference • In current scheme all MSs are connected to AP • Difference CAC design • Different focus (MAC overhead) • Only horizontal handover

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